Method of making tubes



Oct. 11, 1938. H. c. HACKETT 2,133,137

' METHOD 9F MAKING TUBES Filed Sept. 20, 1937 INVENTOR ATTORNEY Patented Oct. 11, 1938 METHOD OF MAKING TUBES Harry 0. Hackett, Wilmington, Del., assignor to National Vulcanized Fibre 00., Wilmington, Del., a corporation of'Delaware Application September 20, 1937, Serial No. 164,800

3 Claims.

The present invention relates to the making of tubes and more particularly to the making of vulcanized fibre tubes having relatively thick walls.

In. the manufacture of tubes made of vulcanized fibre and other chemically treated material in sheet form the general practice has been to wind the material upon a mandrel until it has reached the required diameter, with due allowance for shrinkage and while this is satisfac-' tory for tubes having relatively thin walls it is most unsatisfactory where a thick or heavy wall tube is desired. Heretofore tubes of thick walled construction made by this ordinary method blister and crack so that one layer of material is 'circumferentially out of contact at various points with the I next adjacent layer of material, or there are radial cracks through several layers. .While there seems to be no general rule as to the number. of layers which can be successfully wound without blistering and cracking because of the various diameters of finished tubes, it is well lmown that up to a certain relatively thin wall thickness no such defects appear. On the other'hand as soon as wall thicknesses beyond 5 this safe maximum thickness are called for, present day methods fail to prevent the layers of material cracking during the drying andfinishing steps.

Some of the objects of the present invention are to provide a method of tube making whereinperfect tubes of any desired thickness can be successfully made; to provide a method wherein cracking, blistering and like defects in tubes of laminated construction are eliminated; to provide a method of tube making wherein thick walled tubes canbe made as perfectly as tubes having thin walls; and to provideother improvements as will hereinafter appear.

In the accompanying drawing Fig. 1 represents a perspective of a tube as partially formed in accordance with the present invention; Fig. 2 represents a perspective of the tube of Fig. 1 mounted upon a mandrel; Fig. 3 represents diagrammatically the step following the stage rep- 5 resented by Fig. 2; and Fig. 4 represents a portion, in perspective, of a finished thick walled tube embodying the method of the invention.

Refen'ing to the drawing-those steps believed helpful in the understanding of the present invention are illustrated and in the following description the making of a vulcanized fibre tube is taken as an example of the application of the invention. The first stage in the'method consists in making a complete finished tube It havll inga relatively'thin wall. Such a tube 10 is I made by winding upon a mandrel the required number of convolutions or layers of treated open .matically severed and the wound mandrel-removed. The tube is now pured, dried and rolled 10 so that the result is a completely finished tube It with a relatively thin wall having no breaks or cracks therein. A mandrel l l is now inserted in the finished tube i0, and the latter then placed in the winding or forming machine. form of such machine is indicated in Fig. 3 wherein. driven rollers l2 and I3 support the tube In in surface contact therewith. The paper stock length It is drawn from a stock roll l5 passing through a treating bath l6 of the 20 character noted .to wind about the tube It and form the encompassing tube portion l1. The desired cohesion between the surface of the tube I 0 and the stock It, as well as the succeeding layers of stock is brought about through pressure 25 applied through the roll l8, and the action of the treating acid which causes the surface of the finished tube to knit into the first superposed layer to form a perfect union. This winding operation continues until the thickness of mate- 30 rial superposed about the tube ID will, after 'shrinkagagive a tube of the predetermined diameter and wall thickness. Following this winding operation the tube is removed to soak in a purifying bath until all excess treating liquid is 35 leached out after which the tube is placed in a drierand thereafter submitted to a rolling under calender rolls whereby to finish the same at the final dimension desired. The shrinkage which occurs during thedrying action is restricted .to 6 I the secondary winding of material since the first winding has completed its shrinking when first subjected to the drying operation. It has been discovered that a.tube made in accordance with the present method has its outer series of pliestightly laminated to the surface of the innerseries of plies, the two surfaces being perfectly cohered throughout the whole-area. Thus while the completed tube consists of two separately formed portions l0 and I7, one encompassed by v the other, the joint or seam between the two sets irregularities or other imperfections ordinarily M One 16 found in tubes of like thickness made by prior one following a completed tube, the invention is not limited in this respect in that a series of winding can be made if found expedient. That is to say each series may become a finished tube to be used as a mandrel for another series, and in this way a unitary wall of maximum thickness can be built up free from cracks and other defects now normally present in tubes of corresponding thickness made by methods heretofore practised.

Having thus described my invention, I claim:

1. The method of making a vulcanized-fibre tube having a relatively thick wall from strip material which consists in first forming a relatively thin walled tube by chemically treating the strip with a gelatinizing agent, winding, puring, drying and rolling the wound strip material to produce a finished tube of a limited dimension, and thereafter using said tube as a mandrel and winding on it additional layers of i similarly treated strip material to build up the tube to a desired dimension, and puring, drying, and rolling the tube to finish the same at its final dimension whereby the thick walled tube formed thereby will not blister or crack.

winding operation, and puring, drying, and rolling the tube to finish the same at its final dimension whereby the thick walled tube formed thereby will not blister or crack.

3. The method of making a vulcanized-fibre tube of strip material having a relatively thick wall free from blisters and cracks which consists in forming a relatively thin walled finished tube of vulcanized-fibre strip material of a dimension where the possibility of blistering or cracking is minimized, and thereafter using said tube as a mandrel and winding on it additional layers of chemically treated strip material to build up a relatively thick walled tube of the desired dimension, and puring, drying and rolling the tube to finish the same at its final dimension.

HARRY C. HACKETI. 

